Using Ru-PdO@MXenes-Nanostructured Electrochemical Immunosensing System for Selective Detection of Multiple Breast Biomarkers (HER2 and MUC1)

Early diagnosis of breast cancer relies on detecting multiple cancer biomarkers, which significantly enhances diagnostic accuracy. In this study, we developed a novel electrochemical dual immunosensor for the simultaneous detection of human epidermal growth factor receptor 2 (HER2) and mucin 1 (MUC1) biomarkers. The sensor is based on Ti₃C₂T_<i>x</i> MXene loaded with ruthenium (Ru)/palladium oxide (PdO) nanostructures Ru/PdO@MXene and poly(aniline-<i>co</i>-pyrrole) copolymer substrate. The Ru/PdO@MXene enhanced stability, sensitivity, and impedimetric performance, while the copolymer improved antibody immobilization. Optimized experimental parameters enabled enhanced sensor sensitivity and selectivity. Electrochemical impedance spectroscopy (EIS) revealed excellent linearity across 1.0 fg mL^-1 to 100 ng mL^-1 for HER2 and 1.0 fg mL^-1 to 200 ng mL^-1 for MUC1. The sensor's detection limits reached 0.26 fg mL^-1 (HER2) and 0.28 fg mL^-1 (MUC1), with outstanding sensitivity of 34.45 and 13.86 ng·mL^-1, respectively. In addition, the sensor demonstrated high selectivity, stability, repeatability, and a detection time of 20 min. Spiked serum sample testing yielded recovery rates of 89.6-102.7% (HER2) and 85.69-105.8% (MUC1). This platform shows great promise for early breast cancer diagnosis and could be extended to other clinically relevant biomarkers.